如何在 UWP 中在多个页面上打印

Question

我有一个在我的 UWP 项目中运行的打印系统。

为了准备我的打印内容，我使用了这个：

（来源： https : //blogs.u2u.be/diederik/post/Printing-from-MVVM-XAML-Windows-8-Store-apps ）

public void RegisterForPrinting(Page sourcePage, Type printPageType, object viewModel)
        {
            this.callingPage = sourcePage;

            if (PrintingRoot == null)
            {
                this.OnStatusChanged(new PrintServiceEventArgs("The calling page has no PrintingRoot Canvas."));
                return;
            }

            this.printPageType = printPageType;
            this.DataContext = viewModel;

            // Prep the content
            this.PreparePrintContent();

            // Create the PrintDocument.
            printDocument = new PrintDocument();

            // Save the DocumentSource.
            printDocumentSource = printDocument.DocumentSource;

            // Add an event handler which creates preview pages.
            printDocument.Paginate += PrintDocument_Paginate;

            // Add an event handler which provides a specified preview page.
            printDocument.GetPreviewPage += PrintDocument_GetPrintPreviewPage;

            // Add an event handler which provides all final print pages.
            printDocument.AddPages += PrintDocument_AddPages;

            // Create a PrintManager and add a handler for printing initialization.
            PrintManager printMan = PrintManager.GetForCurrentView();

            try
            {
                printMan.PrintTaskRequested += PrintManager_PrintTaskRequested;
                this.OnStatusChanged(new PrintServiceEventArgs("Registered successfully."));
            }
            catch (InvalidOperationException)
            {
                // Probably already registered.
                this.OnStatusChanged(new PrintServiceEventArgs("You were already registered."));
            }
        }

private void PreparePrintContent()
        {
            // Create and populate print page.
            var printPage = Activator.CreateInstance(this.printPageType) as Page;

            printPage.DataContext = this.DataContext;

            // Create print template page and fill invisible textblock with empty paragraph.
            // This pushes all real content into the overflow.
            firstPage = new PrintPage();
            firstPage.AddContent(new Paragraph());

            // Move content from print page to print template - paragraph by paragraph.
            var printPageRtb = printPage.Content as RichTextBlock;
            while (printPageRtb.Blocks.Count > 0)
            {
                var paragraph = printPageRtb.Blocks.First() as Paragraph;
                printPageRtb.Blocks.Remove(paragraph);

                var container = paragraph.Inlines[0] as InlineUIContainer;
                if (container != null)
                {
                    // Place the paragraph in a new textblock, and measure it.
                    var measureRtb = new RichTextBlock();
                    measureRtb.Blocks.Add(paragraph);
                    PrintingRoot.Children.Clear();
                    PrintingRoot.Children.Add(measureRtb);
                    PrintingRoot.InvalidateMeasure();
                    PrintingRoot.UpdateLayout();
                    measureRtb.Blocks.Remove(paragraph);

                    // Apply line height to trigger overflow.
                    paragraph.LineHeight = measureRtb.ActualHeight;
                }
                firstPage.AddContent(paragraph);
            };

            // Send it to the printing root.
            PrintingRoot.Children.Clear();
            PrintingRoot.Children.Add(firstPage);
        }

PrintPage

public sealed partial class PrintPage : Page
    {
        public PrintPage()
        {
            this.InitializeComponent();
        }

        public PrintPage(RichTextBlockOverflow textLinkContainer)
            : this()
        {
            textLinkContainer.OverflowContentTarget = continuationPageLinkedContainer;
        }

        internal void AddContent(Paragraph block)
        {
            this.textContent.Blocks.Add(block);
        }
    }

<RichTextBlock x:Name="textContent"
                           Grid.Row="1"
                           Grid.ColumnSpan="2"
                           FontSize="18"
                           OverflowContentTarget="{Binding ElementName=continuationPageLinkedContainer}"
                           IsTextSelectionEnabled="True"
                           TextAlignment="Left"
                           FontFamily="Segoe UI"
                           VerticalAlignment="Top"
                           HorizontalAlignment="Left">
</RichTextBlock>

<RichTextBlockOverflow x:Name="continuationPageLinkedContainer" Grid.Row="2" />

该sourcePage

<RichTextBlock x:Name="PrintContent">
        <!-- Content -->
    </RichTextBlock>

我的程序设置方式需要能够在单独的页面上打印 RichTextBox 的每个段落。

这可能吗？

Answer 1

我需要能够在单独的页面上打印 RichTextBox 的每个段落。

如果要在单独的页面上打印 RichTextBox 的每个段落，则需要为每个段落创建多个 PrintPage，然后将 PrintPage 放入 PrintingRoot 和 PrintPages 列表。 之后，当您添加预览页面时，您需要迭代 PrintPages 并添加它们。

我做了以下更改，这里有一个完整的示例，您可以下载并检查它。

private void PreparePrintContent()
{
    PrintingRoot.Children.Clear();
    // Create and populate print page.
    var printPage = Activator.CreateInstance(this.printPageType) as Page;

    printPage.DataContext = this.DataContext;

    var printPageRtb = printPage.Content as RichTextBlock;
    while (printPageRtb.Blocks.Count > 0)
    {
        PrintPage firstPage = new PrintPage();
        firstPage.AddContent(new Paragraph());
        var paragraph = printPageRtb.Blocks.First() as Paragraph;
        printPageRtb.Blocks.Remove(paragraph);

        firstPage.AddContent(paragraph);
        NeedToPrintPages.Add(firstPage);
        PrintingRoot.Children.Add(firstPage);
    };
}

private RichTextBlockOverflow AddOnePrintPreviewPage(RichTextBlockOverflow lastRTBOAdded, PrintPageDescription printPageDescription,int index)
{
    ......
    if (lastRTBOAdded == null)
    {
        // If this is the first page add the specific scenario content
        page = NeedToPrintPages[index];
    }
    ......
}

private void PrintDocument_Paginate(object sender, PaginateEventArgs e)
{
    // Clear the cache of preview pages 
    printPreviewPages.Clear();
    this.pageNumber = 0;

    // Clear the printing root of preview pages
    PrintingRoot.Children.Clear();
    for (int i = 0; i < NeedToPrintPages.Count; i++) {
        // This variable keeps track of the last RichTextBlockOverflow element that was added to a page which will be printed
        RichTextBlockOverflow lastRTBOOnPage;
        // Get the PrintTaskOptions
        PrintTaskOptions printingOptions = ((PrintTaskOptions)e.PrintTaskOptions);

        // Get the page description to deterimine how big the page is
        PrintPageDescription pageDescription = printingOptions.GetPageDescription(0);

        // We know there is at least one page to be printed. passing null as the first parameter to
        // AddOnePrintPreviewPage tells the function to add the first page.
        lastRTBOOnPage = AddOnePrintPreviewPage(null, pageDescription,i);

        // We know there are more pages to be added as long as the last RichTextBoxOverflow added to a print preview
        // page has extra content
        while (lastRTBOOnPage.HasOverflowContent && lastRTBOOnPage.Visibility == Windows.UI.Xaml.Visibility.Visible)
        {
            lastRTBOOnPage = AddOnePrintPreviewPage(lastRTBOOnPage, pageDescription,i);
        }

    }

    PrintDocument printDoc = (PrintDocument)sender;

    // Report the number of preview pages created
    printDoc.SetPreviewPageCount(printPreviewPages.Count, PreviewPageCountType.Intermediate);
}